1. Field of the Invention
The present invention relates to a squeeze roller assembly of a wet type developer for an electrophotographic printer and, more particularly, to a squeeze roller assembly for removing a liquid carrier from a developing liquid which is supplied to the photosensitive medium of an electrophotographic printer.
2. Description of the Related Art
In general, a wet type developer is used for developing a desired latent image on an imaging surface of a photosensitive medium such as a photosensitive belt. A squeeze roller assembly creates a film of solid toner, which is contained in the developing liquid, on to the imaging surface by compressing the imaging surface of the photosensitive belt and squeezing away the liquid carrier.
As shown in FIGS. 1 and 2, a conventional squeeze roller assembly 210 comprises a first squeeze roller 211 and a second squeeze roller 212. The first squeeze roller 211 is installed to contact an imaging surface 111 of a photosensitive belt 11 and to be passively driven by the photosensitive belt 11 in the same direction as the movement of the belt. The second squeeze roller 212 is installed to contact both edges 111b of the photosensitive belt 11 and to be driven by a predetermined driving source (not shown) in an opposite direction in which the photosensitive belt 11 proceeds. The developing liquid for forming an image is supplied to the central portion 111a of the imaging surface 111. Reference numeral A denotes a contact line on which the first squeeze roller 211 and the photosensitive belt 11 are contacted. Reference numeral 213 denotes a developing roller for delivering the developing liquid I.sub.1 supplied through an injection nozzle 10 into the imaging surface 111 of the photosensitive belt 11. Reference numeral 214 denotes a cleaning roller for cleaning the photosensitive roller 213. The developing liquid I.sub.1 contains a liquid carrier I.sub.2.
The first squeeze roller 211 compresses the imaging surface 111, rotating in the same direction as that of the conveying direction of the photosensitive belt 11, to film the solid toner contained in the developing liquid I.sub.1 onto the imaging surface 111 and to remove the liquid carrier I.sub.2 contained in the developing liquid I.sub.1 from the imaging surface 111. The carrier I.sub.2, which is removed as mentioned above, runs down along the downstream side of the first squeeze roller 211 and drips to the inside of the main body 20. However, the remaining liquid carrier I.sub.3, which is pushed outward toward opposite ends of the first squeeze roller 211, goes over both ends 211a (FIG. 2) of the first squeeze roller 211, and resides in an area W of both edges 111b of the photosensitive belt 11. This is generally called a wrap-around phenomenon.
The wrap-around phenomenon is a type of capillary tube phenomenon, which occurs because the first squeeze roller 211 which contacts the first photosensitive belt 11 rotates in the same direction as that of the proceeding direction of the photosensitive belt 11. To remove the carrier I.sub.3 residing in the area W of both edges 111b of the photosensitive belt 11, the second squeeze roller 212 is rotated in the direction opposite to the conveying direction of the photosensitive belt 11 and first squeeze roller 211.
In the conventional squeeze roller assembly 210 having the above structure, the structure is complicated and the main body 20 of the developer must be large in order to secure the installation space for the squeeze rollers 211 and 212 since the first squeeze roller 211 and the second squeeze roller 212 are installed on separate rotating axes.